Help with Sound reduction

Hello.

I currently own a home that has a 2 bedroom apartment and my current tenants are moving out today. We have a young couple moving in at the end of the month but they only wanted a 1 bedroom apartment so I am going to close off a door and turn it into a home theater.

The only problem is that on the other side of the largest wall is the apartment living room so I was hoping for some ideas to help reduce the amount of noise without major renovations.

I was told placing a large rug on the floor and some acoustic panels to help a bit but is there anything else I can do as well?